要配置文件main.php中查看
'assetManager' => [
    'bundles' => [
        'yiiwebJqueryAsset' => [
            'js'=>[]
        ],
        'yiibootstrapBootstrapPluginAsset' => [
            'js'=>[]
        ],
        'yiibootstrapBootstrapAsset' => [
            'css' => [],
        ],
    ],
],
UPDATE
As Soju mentioned in comments, another alternative way would be disabling these files in AppAsset class, which is located in ./assets/, then remove the following lines:
public $depends = [
   'yiiwebYiiAsset',              #REMOVE
   'yiibootstrapBootstrapAsset',  #REMOVE
];
